About.com Guide

By Marcia Purse

July 28, 2011

The FDA has announced there have been serious central nervous system reactions when the antibiotic Zyvox (generic linezolid) or methylene blue, a drug mostly used as a diagnostic dye, is taken with antidepressants. Either combination can cause Serotonin Syndrome, a toxic buildup of serotonin in the brain which may lead to a cluster of symptoms such as confusion, hyperactivity, memory problems, muscle twitching, excessive sweating, shivering or shaking, diarrhea, trouble with coordination, and/or fever.The reason is that Zyvox and methylene blue both act as monoamine oxidase inhibitors, better known as MAOIs . MAOIs are a class of antidepressants that interact dangerously with other antidepressants for the exact same reason – causing Serotonin Syndrome.The FDA’s warnings state that healthcare professionals and patients may not realize that Zyvox and methylene blue have MAOI properties. Neither drug should generally be given to patients taking serotonergic drugs (including all antidepressants) except in life-threatening cases where the need Zyvox or methylene blue is determined to be critical. In those cases, careful monitoring for symptoms of serotonin syndrome must be done.

The conditions these two drugs treat are serious infections and, in the case of methylene blue, cyanide poisoning. But since methylene blue is also used as a dye in diagnostic tests, patients taking antidepressants who are having tests using dye should tell doctors and technicians about the antidepressants they’re taking and ask whether the dye is, in fact, methylene blue. The antidepressant drugs included in this warning are:

All SSRIs (e.g., Prozac, Paxil)

All SNRIs (e.g., Cymbalta, Effexor)

All tricyclics (e.g., amitriptyline, nortriptyline)

All MAOIs (e.g. Nardil, Parnate)

All atypical antidepressants (e.g. trazodone, mirtazepine)

No other drugs have been named as interacting with these two medications, but all your doctors should always know which drugs you are taking, and if you are uneasy at any time, remind them.